Metal flashing thicknesses

Inconsistencies in building codes can lead to confusion


Roofing professionals know metal flashings can play important roles in properly terminating at roof perimeters and providing weathertightness for penetrations. However, there is little agreement regarding the thicknesses of metals to be used for specific metal flashing conditions. The following offers some guidance.

Code requirements

Building codes generally provide for minimum metal thicknesses used in roof systems. For example, the International Building Code,® 2015 Edition (IBC 2015), Section 1503.2-Flashings indicates: "… Where flashing is of metal, the metal shall be corrosion resistant with a thickness of not less than 0.019 inch (0.483 mm) (No. 26 galvanized steel)."

An identical statement is made in the International Residential Code,® 2015 Edition (IRC 2015), Section R903.2-Flashing.